This invention is generally directed to titanyl phthalocyanines and processes for the preparation thereof, and more specifically the present invention is directed to mixtures of titanyl phthalocyanines, especially Type IV, and perylenes, such as those illustrated in U.S. Pat. No. 4,882,254, the disclosure of which is totally incorporated herein by reference. In embodiments, the present invention is directed to processes of improving the cyclic stability of infrared absorbing photogenerating pigments like titanyl phthalocyanine (TiOPc), especially the Type IV titanyl phthalocyanine. Also, the addition of titanyl phthalocyanines, such as Type IV, to perylenes like benzimidazole perylenes increases the photosensitivity of the perylenes especially at 670 nanometers, and further enables the provision of a photoconductor, or imaging member with excellent photosensitivity at wavelengths of from between about 700 to about 840 nanometers wherein the photosensitivity of benzimidazole perylenes (BZP) is known to decrease.
Imaging members with a number of photogenerating pigments, including BZP, titanyl phthalocyanines, metal free phthalocyanines, vanadyl phthalocyanines, and the like, are known. There are illustrated in U.S. Pat. No. 4,882,254, layered imaging members with perylenes, such as benzimidazoles and mixtures thereof, with phthalocyanines, such as vanadyl phthalocyanines, see column 3 of this patent for example. Also known are layered imaging members with certain photogenerating pigments like selenium and charge transport aryl diamines, reference U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. The aforementioned photoresponsive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible with toner compositions of the appropriate charge. Generally, the imaging members containing phthalocyanines are sensitive in the wavelength regions of from about 700 to about 850 nanometers, thus diode lasers can be selected as the light source.
In U.S. Pat. No. 4,728,592, there is illustrated, for example, the use of alpha type TiOPc (Type II) in an electrophotographic device having sensitivity over a broad wavelength range of from 500 to 900 nanometers. This form was prepared by the treatment of dichlorotitanium phthalocyanine with concentrated aqueous ammonia and pyridine at reflux for 1 hour. Also described in the aforementioned patent is a beta Type TiOPc (Type II) as a pigment, which is believed to provide a much poorer quality photoreceptor.
In Konica Japanese 64-17066/89, there is disclosed, for example, the use of a new crystal modification of TiOPc prepared from alpha type pigment (Type II) by milling it in a sand mill with salt and polyethylene glycol. This pigment had a strong XRPD peak at a value of 2 theta of 27.3 degrees. This publication also discloses that this new form differs from alpha type pigment (Type II) in its light absorption and shows a maximum absorbance at 817 nanometers compared to alpha type, which has a maximum at 830 nanometers. The XRPD shown in the publication for this new form is believed to be identical to that of the Type IV form previously described by Sanyo-Shikiso in JOP 63-20365. The aforementioned Konica publication also discloses the use of this new form of TiOPc in a layered electrophotographic device having high sensitivity to near infrared light of 780 nanometers. The new form is indicated to be superior in this application to alpha type TiOPc (Type II). Further, this new form is also described in U.S. Pat. No. 4,898,799.
Generally, layered photoresponsive imaging members are described in a number of U.S. patents, such as U.S. Pat. No. 4,265,900, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material, which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
The following copending patent applications illustrate processes for the preparation of titanyl phthalocyanines, including Type IV in some instances and layered imaging members thereof.
In a copending application U.S. Ser. No. 537,714, the disclosure of which is totally incorporated herein by reference, there are illustrated photoresponsive imaging members with photogenerating titanyl phthalocyanine layers prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance as low dark decay characteristics result and higher photosensitivity is generated, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example U.S. Pat. No. 4,429,029 mentioned hereinbefore.
In U.S. Pat. No. 5,153,313 (D/90244), the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of phthalocyanine composites which comprises adding a metal free phthalocyanine, a metal phthalocyanine, a metalloxy phthalocyanine or mixtures thereof to a solution of trifluoroacetic acid and a monohaloalkane; adding to the resulting mixture a titanyl phthalocyanine; adding the resulting solution to a mixture that will enable precipitation of said composite; and recovering the phthalocyanine composite precipitated product.
In U.S. Pat. No. 5,206,359, there is disclosed a process for the preparation of titanyl phthalocyanine which comprises the treatment of titanyl phthalocyanine Type X with a halobenzene; U.S. Pat. No. 5,189,156 discloses a process for the preparation of titanyl phthalocyanine which comprises the reaction of a titanium tetraalkoxide and diiminoisoindolene in the presence of a halonaphthalene solvent; dissolving the resulting Type I titanyl phthalocyanine in a haloacetic acid and an alkylene halide; adding the resulting mixture slowly to a cold alcohol solution; and thereafter isolating the resulting Type X titanyl phthalocyanine with an average volume particle size diameter of from about 0.02 to about 0.5 micron; and thereafter redispersing the Type X titanyl phthalocyanine in chlorobenzene in order to convert it to the titanyl phthalocyanine Type IV polymorph which is isolated by filtration. U.S. Pat. No. 5,189,155 discloses a process for the preparation of titanyl phthalocyanine Type I which comprises the reaction of titanium tetraalkoxide and diiminoisoindolene in the presence of a halonaphthalene solvent. More specifically, in one embodiment of this copending application there are provided processes for the preparation of titanyl phthalocyanine (TiOPc) Type X polymorphs which comprises the solubilization of a titanyl phthalocyanine Type I, which can be obtained by the reaction of DI.sup.3 and titanium tetrabutoxide in the presence of a solvent, such as chloronaphthalene, reference U.S. Pat. No. 5,189,156 the disclosure of which is totally incorporated herein by reference, in a mixture of trifluoroacetic acid and methylene chloride, precipitation of the desired titanyl phthalocyanine Type X, separation by, for example, filtration, and thereafter subjecting the product to washing with fluorobenzene. The product can be identified by various known means including X-ray powder diffraction (XRPD). The disclosures of each of the aforementioned patents are totally incorporated herein by reference.